The Costs of ESD (Electrostatic Discharge) in Manufacturing Electronics

Fundamentally, ESD (electrostatic discharge) is a discharge of static energy that emits heat, light, and sound.

Lightning is the most powerful form of electrostsatic discharge (ESD): a release of light, heat, and sound.

However, in electronics manufacturing, ESD mostly occurs at micro scales invisible to our senses of sight and sound.

This is problematic because we cannot detect it easily. In fact, most ESD damage can only be seen with the aid of a microscope.

Worse, we know from controlled testing[1] that merely having an ESD Program that mandates all personnel wear wrist straps and use ESD safe transport materials can significantly reduce device failures.

In 1983, Western Electric found that implementing an ESD Program reduced up to 75% of the device failures they were experiencing at one of their plants.

Founded in 1982, the ESD Association is a professional voluntary association dedicated to advancing the theory and practice of electrostatic discharge (ESD) avoidance. From fewer than 100 members, the Association has grown to more than 2,000 members throughout the world. From an initial emphasis on the effects of ESD on electronic components, the Association has broadened its horizons to include areas such as textiles, plastics, web processing, cleanrooms, and graphic arts.

In the United States, the standards used in ESD Programs are codified by the American National Standards Institute which has adopted ESD Association (a global association) standards.

So how do you read the results from measuring? You reference the Triboelectric Series. This is how you will know if something is a conductor or static dissipative, meeting a standard, and develop your control limits.

Material Type

Ohms Resistance

Conductors

Less Than 1 x 106 Ohms (1 megohm)

Static Dissipative (ESD Recommendations)

Between 1 x 106 Ohms (1 megohm) and 1 x 109 Ohms (1 gigaohm)

Static Dissipative (Anti-Static)

Between 1 x 109 Ohms (1 gigaohm) and less than 1 x 1012 ohms

Insulators

Greater Than 1 x 1012 ohms

Grounding vs Ionization

So how do you deal with insulators? You can create pathways for electrons to travel around the insulators into the ground. This is known as grounding.

You can also ionize air molecules so that charge is blown off insulative surfaces. This is known as ESD ionization.

Grounding involves using a mat and a wrist strap to conduct static to ground.

This involves connecting grounding cables to the mat so that it is plugged into electrical sockets with ground connections.

If you consider implementing an ESD Program keep in mind that grounding is generally cheaper than ionization. However, for static being created inside a machine or by fast-moving assembly lines ionization is almost the only way to ensure charge decay.

Notes

Western Electric North Andover Works (1983). “ESD – How Often Does It Happen?” G.T. Dangelmayer, EOS-5, pp.1-5, 1983.